FrankTheRank - 4:13 pm on May 14, 2012 (gmt 0)
So I am informed although I haven't tried it yet.
It helps if you make lots more pages on the bad site, the same name etc as the target before you hit it (word from the @negativeseo guy has it).
These pages can be filled up with duplicate content apparently.
What I have personally seen demonstrated as successful negative attacks is to sites that have built another site to niche off their main brand site.
They have then 301'd the old pages to the new site and left the old keyword rich navigation links in place.
Where they own a lot of sites covering their niche they invariably at the advice of the in-house seo team (and Google), create 301's in a kind of giant linkwheel!
Spam the hell out of the 301's and watch the wheel rotate, and the site burn in very little time, so I am reliably informed!